1. Technical Field
The present invention relates to an ultrasound measurement apparatus which measures a biological tissue by ultrasound measurement, or the like.
2. Related Art
Biological information in a body is measured by an ultrasound measurement apparatus to evaluate a vascular function or to diagnose a vascular disease.
For example, as one of the biological information, the IMT (Intima Media Thickness) of a carotid artery as an index of arteriosclerosis is measured. During the measurement relating to the IMT or the like, the carotid artery needs to be found and a measurement point needs to be appropriately determined. Normally, an operator applies an ultrasound probe over the neck, finds the carotid artery to be measured while viewing a B-mode image displayed on a monitor, and manually sets the found carotid artery as a measurement point.
In the related art, although a lot of skill to promptly execute a sequence of measurement operations and to appropriately find a carotid artery is required, in recent years, a function which supports the measurement operations has been devised. For example, JP-A-2008-173177 discloses a method which automatically detects a vascular wall using reflected wave signal strength from a biological tissue obtained by processing amplitude information of a received reflected wave and the moving velocity of the biological tissue obtained by processing phase information of the received reflected wave. Specifically, the boundary of the vascular wall and the blood flow region is detected based on a first finding that “the strength of the reflected wave signal in the blood flow region of the blood vessel extremely decreases compared to the strength of the reflected wave signal in the vascular wall” and a second finding that “the moving velocity calculated from the phase information of the reflected wave signal is fast in the blood flow region and is slow in the vascular wall”.
However, in the detection method disclosed in JP-A-2008-173177, while a blood vessel can be detected, it is not possible to determine whether the blood vessel is an artery or a vein.
In general, since an artery should be accompanied by pulsation and a vein should not be accompanied by pulsation, it is carelessly considered that an artery and a vein can be identified according to the presence/absence of pulsation. However, in a vascular region, such as an internal jugular vein, which is comparatively close to the heart, right atrial contraction and ventricular contraction may propagate and even a vein may be accompanied by pulsation. For this reason, accurate identification merely based on the presence/absence of pulsation may be difficult.